“…It was comparable with N fertilization in Valencian Community region areas with intensive agricultural production in Spain, in which nitrogen fertilization in pepper and tomato cropping system could reach to 1030 and 940 kg N ha À1 , respectively (Ramos et al, 2002). Fertilizer N use efficiency in intensively managed greenhouse vegetable systems can be less than 10% using conventional management practices (Zhu et al, 2005), consequently large amounts of unused nitrogen are released to the environment through nitrate leaching, denitrification and NH 3 volatilization (Cabrera et al, 1993;Cabrera and Chiang, 1994;Fox et al, 1996;Gollany et al, 2004;Ramos et al, 2002). For example, nitrate-N concentrations in shallow wells around greenhouses in Huimin, Shandong, ranged from 9 to 274 mg N L À1 , with 99% of surveyed wells exceeding the USEPA limit of 10 mg N L À1 , more than half of the samples (53%) exceeding 50 mg N L À1 , and 26% exceeding 100 mg N L À1 (Ju et al, 2006).…”